The present application relates to air dryer purge air cleaners, and is particularly directed to an absorbent apparatus for an air dryer purge air cleaner and method of producing the same. As an example, the absorbent apparatus can be used in a vehicle air brake charging system, such as a truck air brake charging system.
A truck air brake charging system includes a vehicle air compressor which builds air pressure for an air braking system. The compressor is typically lubricated by an engine oil supply. A governor controls system air pressure between a preset maximum and minimum pressure level by monitoring the air pressure in a supply reservoir. When the supply reservoir air pressure becomes greater than that of a preset “cut-out” setting of the governor, the governor controls the compressor to stop the compressor from building air and also causes an air dryer downstream from the compressor to go into a purge mode. As the supply reservoir air pressure drops to a preset “cut-in” setting of the governor, the governor returns the compressor back to building air and the air dryer to air drying mode.
The air dryer is an in-line filtration system that removes water vapor, water droplets, oil droplets, and oil aerosols from the compressor discharge air after it leaves the compressor. This results in cleaner, drier air being supplied to the air braking system, and aids in the prevention of air line and component freeze ups in winter weather. The air dryer typically uses a replaceable cartridge containing a desiccant material and an oil separator. Most of the oil droplets are removed by the oil separator as the air passes into the air dryer. The air then moves through the desiccant material which removes most of the water vapor.
When the air pressure in the supply reservoir reaches the preset cut-out setting of the governor, the governor makes the compressor stop building air and allows the air dryer's “purge cycle” to begin. During the purge cycle, the desiccant material is regenerated (i.e., its ability to remove water is renewed) by a reversal of the saturation process. A small amount of dry air passes back through the desiccant material and the water that has been collected, as well as any oil droplets collected by the oil separator, are purged out through a purge valve to atmosphere. Since the purged air from the purge valve contains oil droplets, this results in depositing of oil onto roadways by the truck. In some known truck air brake charging systems, the purged air passes through a purge air cleaner to remove oil contained in the purged air before directing the cleaned air to atmosphere. Accordingly, those skilled in the art continue with research and development efforts in using purge air cleaners to remove oil contained in purged air from purge valves.